Proportional solenoid



Oct. 27, 1964 B. E. DUFF PROPORTIONAL SOLENOID Filed July 16, 1962 1N VEN TOR. 5/74 5 Duff United States Patent Billy E. Duff, Tulsa, Oida, assignor, by mesne assignments, to Midwestern instruments, line, Tulsa, Okla, a corporation of @ldahorna Filed .luly 16, 1962, Ser. No. ZltMlElZ 4 @laims. (i. 317 188) This invention relates to an electric-mechanical actuator, and more particularly, to an electrically actuated solenoid which is to be employed in displacing mechanical apparatus through small distances by the application of relatively large forces on such apparatus.

It is the primary object of the present invention to provide a solenoid of relatively small dimensions for use in displacing heavy duty mechanical apparatus and wherein the solenoid is provided with an armature adapted to be coupled with the apparatus, and a pair of electrical current-carrying coils on opposed sides of the armature and capable of creating high-density magnetic fields, whereby large magnetic forces may be exerted on the armature to deflect the same and thereby displace the mechanical apparatus coupled therewith toward one of the coils when an electric signal is passed through the coil, or when an unbalance of magnetic force exists between the coils due to electrical currents of differing magnitudes passing therethrough, notwithstanding the small size of the solenoid and its component parts.

A further important object of the present invention is the provision of a relatively stiff spring for mounting the armature on a support for movement in opposed directions between a pair of pole pieces operably coupled with the coils, whereby the armature is deflected a predetermined distance toward one of the coils proportional to the magnitude of the electric signal passing through the coil and until the magnetic force created by the passage of the signal through the coil is equal and opposite to the restoring force of the spring.

Another object of the present invention is the provision of a spring of the aforesaid character which has a relatively high natural frequently and is capable of being deflected only through a relatively small distance by virtue of its stilfness characteristics, whereby the spring provides an accurate centering device for the armature for positioning the latter substantially midway between the pole pieces, while at the same time, the spring renders the armature substantially incapable of lateral acceleration in directions toward the pole pieces when the armature moves in said directions under the influence of the magnetic forces created by the passage of electric signals through the coils.

Other objects of this invention will become apparent as the following specification progresses, reference being had to the accompanying drawing, wherein:

FIGURE 1 is a side eievational view of the solenoid which forms the subject of the present invention, parts being broken away and in section to illustrate details of construction;

FIG. 2 is an end elevational view of the solenoid;

FIG. 3 is a top plan view of the solenoid of FIGS. 1 and 2;

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 1;

FIG. 5 is a cross-sectional view taken along line 55 of FIG. 3; and

FIG. 6 is a perspective view of the armature and the spring for mounting the armature on a support for movement between a pair of spaced coils forming parts of the solenoid.

The present invention provides a solenoid to be used in displacing mechanical apparatus through small distances by the application of large magnetic forces to an armature disposed between a pair of spaced pole pieces surrounded by respective electrical current-carrying coils. A spring having a relatively high natural frequency interconnects the armature with a support so that the armature is movable toward the pole pieces under the influence of magnetic forces created about the coils as a result of the passage of electric signals through the coils. The armature moves in a direction toward one of the pole pieces until the restoring force of the spring is equal and opposite to the magnetic force exerted on the armature. When the signal is removed from a corresponding coil, the restoring force of the spring returns the armature to its null or equilibrium position and thereby returns the apparatus coupled with the armature to the equilibrium position of the apparatus.

The solenoid of the present invention is broadly denoted by the numeral 1th and includes a support 12 in the nature of a plate 14 to which a pair of spaced pole pieces 16 and 18 are afiixed by means of machine screws 20, as is clear in FIGS. 1 and 2. A spacer bar 22 spans the distance between, and is secured to pole pieces 16 and 18 in the manner shown in FIGS. 1, 3 and 4. Spacer bar 22 is thus spaced from plate 14 and is secured to pole pieces 16 and 13 by machine screws 24 threaded into axially aligned bores in spacer bar 22 as is clear in FIG. 4. By virtue of the presence of plate 14 and spacer bar 22, the pole faces 26 and 28 of pole pieces 16 and 18 are substantially parallel and are spaced a predetermined distance apart.

Pole pieces 16 and 13 are provided with electrical current-carrying coils 3t) and 32 surrounding cylindrical portions 3d and 36 forming integral parts of pole pieces 16 and 18 respectively. Pole pieces 16 and 18 are provided with aligned openings 37 therethrough which terminate at pole faces 26 and' 28 respectively.

An armature, broadly denoted by the numeral 38, is illustrated in FIG. 6 and includes a semicircular section 4t) of a predetermined thickness formed of a material having a relatively high magnetic susceptibility. A pair of circular bosses 42 are integral with opposed faces of section 4d, and a threaded bore 44 passes through section 40 and bosses 42, as is clear in FIGS. 4 and 6. A setscrew 4-5 extends into section 4t) and bears against structure threaded Within bore 44.

Plate 14 is provided with a pair of spaced, transverse portions 46 extending from plate 1 toward spacer bar 22. Portions 46 are spaced apart to form an opening 48 aligned with a similar opening 5% in plate 14. A circular boss 52 is integral with plate 14 and provided with a bore 54 therein aligned with openings 48 and 50.

An elognated spring member 56 is provided with a cylindrical end portion 58 received within bore 54 so that the main body portion of spring 56 extends through openings 48 and 5% as is clear in FIG. 5. The opposite end 59 of spring 56 is enlarged and received within a recess 69 in section it). Portions 58 and 59 are preferably press-fitted within bore 54 and recess 66), and suitably aflixed to boss 52 and section 40 respectively in any suitable rnanner, such as by welding, brazing or the like.

By virtue of the aforesaid construction, armature 38 is cantilevered on boss 52 and movable toward pole faces 26 and 28 by virtue of the construction of spring 56, it being noted that the latter is provided with a pair of 0pposed side faces 62 which are substantially parallel and separated by a predetermined thickness of material. Further, it is to be noted that armature 38 moves in a plane substantially perpendicular to the planes of faces 62. It can be seen that spring 56 is provided with a relatively high natural frequently and provides a device for accurately centering armature 38 midway between pole faces 26 and 28.

In operation, electric signals may be passed through coils 3i) and 32 by intercoupling the lead wires 64 and 66 of coils 30 and 32 respectively to sources of the signals. Also, only one of the coils 3i and 32 may be energized at any one time so that when a signal is impressed on one of the coils, armature 38 is caused to deflect toward such coil under the influence of the magnetic field created by the passage of the signal through the coil.

Mechanical apparatus, such as linkage structure, may be passed through one of openings 37 into threaded bore 44 of armature 38, it being noted that bore 44 is normally aligned with openings 37. An electric signal may be passed into and through coil 39 for instance, and the corresponding boss 42 of armature 38 will be attracted to pole piece 26 under the influence of the magnetic field passing through portion 34 and about coil 3th. As armature 38 is deflected, the linkage structure coupled therewith, is displaced in the direction toward portion 34 until the restoring force of spring 56 is equal and opposite to the magnetic force of attraction. Immediately upon the removal of the electric signal from coil 3d, the restoring force of spring 56 returns armature 38 to its null or equilibrium position.

Similarly, if an eletcronic signal is passed through coil 32, the corresponding boss 42 is attracted to pole face 28 to thereby shift armature 38 and the linkage structure coupled therewith in the opposite direction until the restoring force of spring $6 once again equals and is opposite to the magnetic force.

It can be seen that electric signals of equal magnitude may be passed through coils 3t) and 32 so that equal and opposite forces will be exerted on armature 38 so as to maintain the latter in the equilibrium position. Should there be an unbalance in the magnitudes of the electric signals, armature 38 will be attracted to the coil having the electric signal of greater magnitude passing therethrough.

Solenoid 10 may be constructed of a size such that the same can be utilized in-confined regions and spaces,

while at the same time, the weights of the various parts are of such value so as to maintain the over-all weight of solenoid 10 at a minimum. Thus, for its weight and size, solenoid 10 provides a highly efiicient electrmmechanicall actuator having low hysteresis characteristics,

while spring 56 of solenoid 10 has a high natural frequency and a relatively large restoring force for small displacements of armature 38. Such structure of spring 56 renders armature 33 incapable of any substantial lateral accelerations as armature 38 moves in opposed directions toward pole pieces 16 and 18.

The displacements of armature 38 are, therefore, proportional to the magnitude of the electric signals passing through coils 3i and 32. Such small displacements of armature 33 may, of course, be magnified by suitable structure adjacent solenoid llll.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In an electromechanical actuator: a pair of pole pieces having opposed, spaced-apart pole faces;

a coil wound on each pole piece respectively,

said coils being spaced-apart and being wound around aligned axes normal to and intersecting corresponding pole faces;

an armature disposed between said faces in alignment with said axes for movement toward and away from said faces in response to energization of the coils;

an elongated spring member rigid to and extending laterally from said armature, terminating in an end remote from the armature,

said member having opposed sides between the armature and said end normally disposed in substantial parallelism with said faces; and

a cantilever support for said end of the member,

permitting swinging movement of the armature toward and away from said faces as the member flexes in the zone of said sides transversely of the latter.

2. The invention of claim 1, said sides being between the coils, and said cantilever support including structure remote from the coils for holding the member against rotation.

3. The invention of claim 1, said pole pieces having aligned openings coaxial with said axes for clearing output elements to be connected with the armature.

4. The invention of claim 1, said armature being semicircular, presenting opposed surfaces normally parallel with said faces and a straight edge having the member connected therewith.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN AN ELECTROMECHANICAL ACTUATOR: A PAIR OF POLE PIECES HAVING OPPOSED, SPACED-APART POLE FACES; A COIL WOUND ON EACH POLE PIECE RESPECTIVELY, SAID COILS BEING SPACED-APART AND BEING WOUND AROUND ALIGNED AXES NORMAL TO AND INTERSECTING CORRESPONDING POLE FACES; AN ARMATURE DISPOSED BETWEEN SAID FACES IN ALIGNMENT WITH SAID AXES FOR MOVEMENT TOWARD AND AWAY FROM SAID FACES IN RESPONSE TO ENERGIZATION OF THE COILS; AN ELONGATED SPRING MEMBER RIGID TO AND EXTENDING LATERALLY FROM SAID ARMATURE, TERMINATING IN AN END REMOTE FROM THE ARMATURE, SAID MEMBER HAVING OPPOSED SIDES BETWEEN THE ARMATURE AND SAID END NORMALLY DISPOSED IN SUBSTANTIAL PARALLELISM WITH SAID FACES; AND A CANTILEVER SUPPORT FOR SAID END OF THE MEMBER, PERMITTING SWINGING MOVEMENT OF THE ARMATURE TOWARD AND AWAY FROM SAID FACES AS THE MEMBER FLEXES IN THE ZONE OF SAID SIDES TRANSVERSELY OF THE LATTER. 